Opinions expressed by Entrepreneur contributors are their own. Taxes are the number-one issue facing small businesses, according to December’s Small Business Optimism survey. As we’re now in tax ...

Income tax — a tax on money made from jobs and other sources — is the largest revenue source for the US government. Although originally controversial, it has become a key principle of the US tax code.

Business owners need a good understanding of required federal, state, and local taxes. Filing business-related taxes can be a time-consuming and complicated process, especially for new entrepreneurs.